Nikon D300 User Manual page 709

Bald Eagle Fishing – Courtesy of David Summers (dm1dave)
With each progressive generation of semi-pro digital SLR
cameras, Nikon has increased the number of autofocus (AF)
points and area modes in the AF system.
For instance, the Nikon D100's Multi-CAM 900 AF module
has 5 AF points and two area modes, and the Nikon D200's
Multi-CAM 1000 has 11 AF points and four area modes. The
D300(S)'s Multi-CAM 3500DX has 51 AF points, but only
three area modes, thereby making the AF system simpler to
operate, yet more robust.
What do we gain from all these extra AF sensor points and
more powerful area modes? Is there anything else new and
different? As we progress through this chapter, we'll discuss
these questions in detail, along with how your photography
will benefit most from the Multi-CAM 3500DX AF system.
What Is the Multi-CAM 3500DX
Autofocus Module?
The Multi-CAM 3500DX autofocus (AF) module is a
thoroughly improved, third-generation version of the
excellent Multi-CAM 1000 autofocus module found in the
Nikon D200. Where the Multi-CAM 1000 is limited to only
11 AF sensors, the Multi-CAM 3500DX has 51. In
Figure 11-1 you can see what the new AF module looks like.
As we proceed through this chapter, I'm going to call the
Multi-CAM 3500DX autofocus module by the simpler name
of AF Module.
The AF Module has three AF-area modes:
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